Ravelry is your go-to resource for all fiber arts. You'll find patterns (free and paid) and tools for organizing your projects. There is a thriving community for support in the forums.
I love this site for their knitting techniques and their quarterly field guides that highlight patterns from super talented designers.
Patty Lyons is a knitting teacher and techniques expert. Follow her on instagram, read her blog, listen to everything she has to say if you want to improve your knitting skills and understanding.
Toni is a crochet designer and instructor. I've linked to her YouTube because her videos are great and really helpful. Her videos include tutorials, tips, tricks, and yarn reviews.
Very Pink Knits' YouTube is a huge collection of knitting tutorials with basic to advanced techniques. I refer to her videos frequently.
If you are interested in learning more about wool and its various types and properties, you have to check out Clara Parkes' community site and newsletter for wool enthusiasts.